Printer with control cam shaft

ABSTRACT

In a printer for printing on individual printing media such as receipts, savings books and the like, a control shaft activated by the printer control system has a plurality of control cams for activation of a transport device, a printing medium alignment means, and a printing medium stop, the cams being designed such that the activation zone of the alignment means and of the printing medium stop are located substantially in the deactivation zone of the transport device.

The invention relates to a printer for printing on individual printingmedia according to the preamble of claim 1. It is based onWO-A-96/01742.

A printer of the type mentioned is marketed under the designation“HighPrint 4905” by Siemens Nixdorf Informationssysteme AG, Paderborn,Germany.

In such a printer, various functions for handling and processing theindividual printing medium have to be controlled. Although thesefunctions proceed in a specific sequence, they do not have to beactivated in the case of all individual printing media. For example,when processing savings books, functions are activated which are notneeded when printing on receipts.

In WO-A-96/01742, it has already been proposed to mount a control shaftsuch that it can rotate in a printer frame, said shaft being capable ofbeing driven by a motor that can be activated by a printer controlsystem and bearing a control curve which controls at least theactivation of the transport device, the activation of the alignmentmeans and the adjustment of the printing-medium stop.

The invention is based on the object of designing a printer of the typementioned at the beginning in such a way that the individual units forhandling a printing medium in the printer can also be operated reliablyand in a straightforward manner without hampering one another.

According to the invention, in a printer of the type mentioned at thebeginning this object is achieved by the features specified in thecharacterizing part of claim 1.

Using the control shaft provided in accordance with the invention, it ispossible to ensure in a straightforward way that a printing mediuminserted into the printer is firstly aligned against the printing-mediumstop and brought into a starting position which is suitable for theprinting operation, before the transport device is set into operation.By means of the arrangement of the control cams on the control shaftrelative to one another, the desired trouble-free progress of thefunctions is ensured.

The transport device can be controlled in a straightforward way by itscomprising at least one driven transport shaft bearing transport rollersand pressure rollers which are associated with the transport rollers andcan be adjusted between a pressure or activation position close to thetransport rollers and a rest or deactivation position away from thetransport rollers. In this case, the motor driving the transport shaftdoes not need to be switched, so that a control system for controllingthe starting and braking of the motor can be dispensed with.

According to a further function, provision is made for the printing barto be adjustable in relation to the printing head by a control cam onthe control shaft between a printing position close to said printinghead and a rest position away from the latter, and by the controlledcurve of the printing-bar control cam being designed such that the restposition of the printing bar is located in the activation zone of thetransport device. On the other hand, that angular range of the controlcurve of the printing-bar control cam which corresponds to the printingposition of the printing bar extends over the deactivation zone andpreferably an adjacent part of the activation zone of the transportdevice.

In order to press the printing medium against the printing bar andtherefore to permit clean printing, there is arranged parallel to theprinting bar a protective film strip on a film carrier, which can beadjusted between a position close to the printing bar and a positionaway from the printing bar. According to the invention, in this case theadjustment of the film carrier can be controlled by a film carriercontrol cam on the control shaft, whose control curve is designed suchthat there is correspondence between the printing position of theprinting bar and the position of the film carrier close to the printingbar, on the one hand, and the rest position of the printing bar and theposition of the film carrier away from the printing bar, on the otherhand. In the rest position of the printing bar, the receipt cantherefore be transported into the printer without hindrance while it ispressed against the printing bar by the film strip in the printingposition of the printing bar, and is therefore held in a positionensuring clean printing.

In the case of specific printing media, it is necessary to obtaininformation about the type of printing medium before the printingoperation. For this purpose, the printer has a reading device which, forexample, is designed for reading characters produced on the printingmedium with magnetic ink, and has at least one magnetic head and a firstprinting-medium pressure device which, according to the invention, canbe activated by a control cam on the control shaft, the control curve ofthis control cam being designed such that the activation zone of thefirst printing-medium pressure device is located in the zonecorresponding to the rest position of the printing bar.

Furthermore, in the printer there can be provided a reading/writingdevice for reading and writing on a magnetic strip on a printing medium,which has a magnetic head arrangement and a second printing-mediumpressure device. According to the invention, this can likewise beactivated by a control cam on the control shaft, the control curve ofthis control cam being designed such that the activation zone of thesecond printing-medium pressure device is located within the activationzone of the first printing-medium pressure device.

It is expedient for the start position and end position of the controlshaft, between which the latter can be rotated to and fro, to be definedby a switching flag arranged on the control shaft.

Further features and advantages of the invention emerge from thefollowing description, which explains the invention using an exemplaryembodiment in conjunction with the appended drawings, in which:

FIG. 1 shows a perspective overall view of a printer according to theinvention without the upper part of the printer housing,

FIG. 2 shows a perspective partial view of a side wall of the printerchassis with the drive for the transport shafts and the control shaft,

FIG. 3 shows a perspective view of the control shaft in a first angularposition,

FIG. 4 shows a perspective view of the control shaft in a second angularposition,

FIG. 5 shows a perspective illustration of the control shaft, thereceipt stop and the pressure rollers in a first position of theseelements,

FIG. 6 shows an illustration corresponding to FIG. 5 in a secondposition of the said elements,

FIG. 7 shows a perspective illustration of the control shaft and of thealignment mechanism in an activated position of the latter,

FIG. 8 shows an illustration corresponding to FIG. 7 of the alignmentmechanism in its deactivated position,

FIG. 9 shows a perspective view of the printing bar and of the filmcarrier,

FIG. 10 shows a schematic side view of a magnetic-strip readingarrangement and a reading arrangement for reading characters produced onthe printing medium with magnetic ink, in a first position of theseelements,

FIG. 11 shows an illustration corresponding to FIG. 10 with the elementsin a second position, and

FIG. 12 shows a timing diagram of the functional sequences of theprinter units as a function of rotational angle and direction ofrotation of the control shaft.

The printer illustrated in FIG. 1 is used for printing individualprinting media such as receipts, savings books and the like. Itcomprises a chassis designated generally by 10 and having a base 12, anouter frame 14 with frame walls 16 and an inner frame 18 with side walls20.

Between the side walls 16 of the outer frame 14 there extends a guiderod 22, on which a carriage 26 bearing a dot-matrix printing head 24 isguided such that it can be displaced to and fro. The carriage is drivenvia a toothed belt 28.

The dot-matrix printing head 24 is arranged in such a way that itsneedles are displaced substantially vertically and the tips of theneedles are oriented downward. The printing head 24 is assigned, as aprinting abutment, a printing bar 30 which extends between the two sidewalls 20 of the inner frame 18, parallel to the guide rod 22. The designand arrangement of the printing bar 30 will be explained in more detailfurther below.

The printing media are moved between a lower cover 32, which has beenpartially removed in FIG. 1; and an upper covering (not illustrated)formed on a housing hood. The movement is carried out with the aid of atransport device, which can be seen better in FIG. 2. It comprises twotransport shafts 34, 36 which are aligned parallel to the guide rod 22,which are at a distance from each other in the transport direction ofthe printing medium indicated by the double arrow A in FIG. 1, and eachbear transport rollers 38 spaced apart axially. The transport shafts 34and 36 are rotatably mounted in the side walls 20 of the inner frame 18and, at their one end projecting beyond the side wall 20, each bear adrive roller 40 and 42, respectively. In addition, a drive motor 44,whose shaft 46 bears a drive pinion 48, is flange-mounted on the sidewall 20 of the inner frame. Said drive pinion drives the transportshafts 34 and 36 via a drive belt 50, which is led over the driverollers 42 and 40 and a tensioning roller 52.

The transport rollers 38 are additionally each assigned pressure rollers54, which are mounted above the transport rollers 38,in each case inpairs, on a carrier 56. The rear pressure rollers 54 associated with therear transport shaft 36 are mounted, with their respective carrier 56,on a transverse strut 58 such that their height can be adjusted. Thecarriers 56 of the front pressure rollers 54 are mounted on the uppercovering (not illustrated) such that their height can be adjusted sothat they can be lifted off the transport rollers 38 or set down ontothe latter, as will be explained in more detail further below.

Also mounted in the side walls 20 of the inner frame 18 is a controlshaft 60 which is oriented parallel to the transport shafts 34 and 36and which, at its one end, bears a gear wheel 62 (FIGS. 2 and 3), viawhich it can be driven by a toothed belt 64, which also runs over adrive pinion 66 of a motor 68. As FIG. 3 shows, the control shaft 60bears a large number of cams for controlling mechanical functions in theprinter, as will be further discussed in detail below.

FIG. 9 shows the printing bar 30 in greater detail. It comprises a flat,rule-like carrier 70, which is stamped from a metal sheet, for example,and a top rail 72, which consists of plastic and is connected to thecarrier 70 along a longitudinal edge of the latter. The top rail has aflat top side 74, which serves as a rest for the printing medium, and onboth long sides, guide noses 76 which fall away downwards and areintended to ensure that the printing medium is guided onto the surface74 of the printing bar 30 as it is transported into the printer.

The printing bar 30 is mounted between the side walls 20 of the innerframe 18 such that it can be adjusted vertically, and is biased into anupper position by a helical compression spring 78 at its long ends ineach case. The helical compression spring 78 is supported on a pinelement 80 which is fixed to the frame and is fastened to the outside ofthe respective side wall 20 (FIG. 1). Associated with the printing bar30, at each of its long ends, is an actuating lever 82, which is mountedsuch that it can be pivoted about a pivot axis 84 on the respective sidewall 20. The actuating lever 82 has a fork-like lever arm 86 which,between the limbs of the fork, holds a lug 88 projecting from thecarrier 70 of the printing bar 30. A second lever arm 90, projectingapproximately at right angles in relation to the fork arm 86, in eachcase rests with its free end 92 on two cam discs 94, which are providedclose to the long ends of the control shaft (FIG. 3). With the aid ofthe actuating lever 82, the printing bar 30 can be adjusted downwards,counter to the bias of the helical compression springs 78, by the camdiscs 94 on the control shaft 60.

Provided parallel to the printing bar 30 is a pressure device 96, whichis used to press the respective printing medium against the surface 74of the printing bar 30, and therefore to ensure a predefined distancebetween the printing-medium surface and the printing head 24. Thepressure device comprises a film carrier 98 and a film strip 100 fixedto the latter (FIG. 9). The film carrier 98 can be clipped in on a rodon the upper covering (not illustrated) with the aid of clips 102, sothat it can be pivoted about the axis 104 of this rod. At its respectivelong end, the foil carrier 98 has a lever 106, on which a helicalcompression spring 108 acts, which is supported by its other end on apart fixed to the frame and biases the film carrier 98 in thecounterclockwise direction in FIG. 9, against the upper side 74 of theprinting bar 30. In addition, the film carrier 98 has, at each of itslong ends, an extension 110 which projects downward and on which a firstlever arm 112 of an actuating lever designated generally by 114 rests.This actuating lever 114 is mounted such that it can rotate about anaxis 116 on the respective side wall 20 of the frame 18 and has a secondlever arm 118, which is intended to rest on a cam disc 120 of thecontrol shaft 60. Therefore, in the event of rotation of the controlshaft 60, the pressure device 96 can be rotated in the clockwisedirection in FIG. 9 counter to the bias of the springs 108, andtherefore lifted off the printing bar 30.

FIGS. 5 and 6 show a receipt stop, generally designated by 122, and alsothe front pressure rollers in two different positions. The receipt stopcomprises an elongate carrier 124, which engages over the control shaft60 and bears a row of stop elements 126, 128 on its upper edge. If thereceipt stop 122 is in its lower position illustrated in FIG. 5, areceipt can be pushed into the printer onto the printing bar 30. In thisposition, the roller carriers 56 are lowered, so that the pressurerollers 54 rest on the transport rollers 38. If the receipt stop 122 isin the upper position, illustrated in FIG. 6, then the stop elements 126and 128 block the path of the printing media and prevent the latterbeing pushed onto the printing bar 30. In this position, the longer stopelements 128 which can be seen in FIGS. 5 and 6 in each case pressagainst extensions 130 on the roller carriers 56 and lift the latter, sothat the pressure rollers 54 no longer have any contact with thetransport rollers 38. The adjustment of the receipt stop 122 is providedby cam discs 132, on which the carrier 124 of the receipt stop 122rests.

The printer further comprises an alignment device, designated generallyby 133, in order to align the printing medium against the receipt stop.This alignment device 133 is illustrated in FIGS. 7 and 8. It comprisesa shaft 136 which is mounted on the chassis base 12 in bearing blocks134 and on which a first coupling sleeve 138 is rotatably mounted, thelatter being capable of being driven by the front transport shaft 34 viaa drive belt 140 (FIG. 1). In addition, a second coupling sleeve 142 ismounted on the shaft 136 such that it can be rotated and displacedaxially; said sleeve can be engaged with the first coupling sleeve 138so as to transmit torque via coupling claws 144 with correspondingcoupling claws 146 on the first coupling sleeve 138. Fixed to the secondcoupling sleeve 142 are approximately triangular alignment rollers 148,which can reach through openings which are formed in the lower covering32, in order to engage with a printing medium lying on the lowercovering 32. In addition, at its end facing away from the first couplingsleeve 138, the second coupling sleeve 142 bears a bevel gear wheel 150,which interacts with a bevel gear wheel 152 aligned at right angles toit in order to drive a further alignment roller 154, whose shaft 155 isoriented at right angles to the shaft 136.

The triangular shape of the rollers 148 and 154 has the effect that theprinting medium lying on the lower covering 32 is lifted up abruptlyand, on the one hand is transported in the direction of the stopelements 126, 128, but on the other hand is transported by the roller154 in the direction of one of the side walls 20 of the frame 18. As aresult, relative to the receipt stop 122, the printing medium is broughtinto a defined starting position for a printing operation.

The alignment device can be switched on and off by the couplingengagement between the two coupling sleeves 138, 142 being made orbroken as desired. For this purpose, use is made of a coupling lever156, which is mounted on the chassis base (in a manner not illustrated)such that it can be rotated about a shaft 158 substantiallyperpendicular to the chassis base 12. A first lever arm 160 of thecoupling lever 156 rests with its free end on the second coupling sleeve142 and is biased by a helical spring 162 with the effect of disengagingthe coupling engagement between the two coupling sleeves 138, 142. Atthe same time, as a result, a second lever arm 164 of the coupling lever156 is urged against an axial cam disc 166 on the control shaft 60. If,as a result of a rotation of the control shaft 60, the coupling lever156 is pivoted in the counterclockwise direction out of the positionillustrated in FIG. 7 into the position illustrated in FIG. 8, theresult is that the coupling engagement between the two coupling sleeves138 and 142 is released, and therefore the drive to the alignmentrollers 148, 154 is interrupted.

Printing media such as savings books or the like generally bear amagnetic strip on which specific information about the holding of thesavings book, account number, account balance and the like are stored.In order to read and write on this magnetic strip, use is made of areading/writing device generally designated by 168, which is arrangedunder the lower covering 32 in such a way that the magnetic gap in themagnetic head lies in the surface of the lower covering 32 and can bedisplaced in the printer transversely with respect to the insertiondirection of the printing medium. Such a reading/writing device is knownper se and therefore does not need to be explained in detail. Thereading/writing device 168 is assigned a pressure device 170 in order topress the printing medium against the magnetic head of thereading/writing device 168. The reading/writing device 168 and thepressure device 170 associated with it are illustrated in FIGS. 10 and11.

The pressure device 170 is arranged on the upper covering of the printerin a manner not specifically illustrated and is biased in the directionof the lower covering 32 by compression springs 172 (FIG. 1). FIG. 11shows the pressure device 170 in its upper position. In this position,it is held by an actuating lever 174, which is guided displaceably onone side wall 20 of the frame 18, in the direction of the double arrow Bin FIG. 11, with the aid of pins 176 which engage in slots 178 in theactuating lever 174. The actuating lever 174 is biased obliquely upwardin FIG. 11 by a compression spring 180, which is supported at one end byan actuating lever 174 and at the other end on a part fixed to theframe, the top end 182 of said lever striking a pivoting lever 184belonging to the pressure device 170 and holding the latter in itslifted position.

At its lower end 186, facing away from the top end 182, the actuatinglever 174 has a pin 188 on which a driver lever 190 can act, said driverlever being connected to the control shaft 60 so as to rotate with itand, according to FIG. 10, in the event of rotation of the control shaft60 in the counterclockwise direction, striking the pin 188 and, in sodoing, pulling the actuating lever 174 obliquely downward counter to thestress of the spring 180. As a result, the pressure device 170 is alsolowered, so that it can press a printing medium lying on the lowercovering 32 against the reading/writing device 168.

FIGS. 10 and 11 also show a reading device, generally designated by 192,for reading characters written with magnetizable ink on a printingmedium. The reading device 192 comprises, in a manner known per se, amagnetization head 194 and a reading head 196. The magnetization head194 has the task of magnetizing the characters printed with magnetizableink on the printing medium so that they can be read by the reading head196. This reading head 196 is in turn assigned a pressure device 198 inorder to press the printing medium against the reading head 196 when thecharacters are to be read. This pressing device 198 has a swinging arm200 which is mounted on the outer frame 14 such that it can be pivotedabout an axis 202 in a manner not illustrated, and bears a pressureroller 204. The swinging arm 200 is biased into its position illustratedin FIG. 10, in which the pressure roller 204 is lifted off the readinghead 196, by a helical compression spring 206, which is supported at oneend on a section (not illustrated) fixed to the frame and at the otherend on an end of the swinging arm 200 that faces away from the pressureroller 204.

In order to adjust the swinging arm 200 into its pressure positionillustrated in FIG. 11, use is made of a pressure lever 208, which ismounted such that it can be pivoted about an axis 210 and presses ontothe swinging arm 200 with its one lever arm 212, while its other leverarm 214 is connected via a hinge 216 to the one end of an actuatinglever 218. The latter is mounted on the outside of the side wall 20 ofthe frame 18 such that it can be displaced translationally in thedirection of the double arrow C in FIG. 11. Its end facing away from thehinge 216 rests on a cam disc 220 of the control shaft 60, with the aidof which the swinging arm 200 can be pivoted, via the linkage 218, 208,between the positions illustrated in FIGS. 10 and 11.

As the above description shows, the pressure rollers 54 interacting withthe transport rollers 38, the receipt stop 122, the printing bar 30, thefoil carrier 98 with the foil strips 100, the coupling sleeve 142 of thealignment device, the pressure device 170 for the magnetic-strip readingand writing device 168, and the pressure device 198 for the readingdevice 192 can all be adjusted by means of the control shaft 60. Theessential factor here is that the cams are arranged on the control shaft60 in such a way that the functions of the above-described parts of theprinter do not hamper one another.

FIG. 12 shows the functional sequences of the above-described devices asa function of the rotational angle and of the direction of rotation ofthe control shaft 60.

The control shaft 60 can be pivoted about a normalization position,which is assigned to the angle 0 up to −73° in one direction of rotationand up to +266° in the other direction of rotation. These limits of thepivoting range of the control shaft 60 are defined by a switching flag222 on the control shaft 60 (FIGS. 3 and 4), which engages in a forkedlight barrier (not illustrated).

The first line of FIG. 12 shows the switching range of the forked lightbarrier. The hatched region to the left of the zero line indicates theregion in which the forked light barrier outputs the signal “light”,that is to say in which it is not interrupted by the switching flag 222.The region lying to the right of the zero line indicates the angularrange of the control shaft 60 in which the switching flag 222 interruptsto beam in the forked light barrier, so that the latter outputs itssignal “dark”.

The second line of FIG. 12 relates to the function of the receipt stop122. Between −73° and −65° the receipt stop is located in its upperposition (hatched region). In this position, the receipt stop blocks theinsertion of a printing medium over the printing bar 30. Between −65°and +52°, the receipt stop is lowered continuously. Once the receiptstop has been lowered completely, the printing medium can be moved asdesired in the printer.

The third line relates to the pressure rollers 54 interacting with thetransport rollers 38. Between −73° and −65°, the pressure rollers assumetheir upper position (hatched region). Between −65° and 0°, the pressurerollers are lowered together with the receipt stop until they rest onthe transport rollers 38. Between 0° and 266°, a printing medium can begripped and transported by the transport rollers 38.

The fourth line of FIG. 12 relates to the alignment device. In thehatched region, the alignment device is switched on, that is to say thealignment rollers 148 and 154 are rotated in order to align the printingmedium against the receipt stop 122. Lines 2, 3 and 4 therefore relateto measures which are used to prepare a print.

Line 5 shows the regions in which the printing bar is lifted and lowered(hatched region from −73° to +155°) and in which the printing bar iscompletely lowered (+155° to 266°). The sixth line, which reproduces thepositions of the pressure film, corresponds to this region. As long asthe printing bar 30 is in its upper position, in which printing can alsobe carried out, the pressure film is in its lower position, in which itpresses the printing medium against the printing bar 30. This regionextends from −73° to +155°. On the other hand, when the printing bar 30is lowered completely, the pressure film 100 is lifted (hatched regionfrom +155° to 266°). When the printing bar 30 is lowered and thepressure film 100 is lifted, printing media can be moved through betweenthe printing bar and the pressure film.

The seventh line reproduces the position of the pressure device 198associated with the reading device 192. The hatched region from −73° to+210° corresponds to the lifted position and the transition of thepressure device 198 into its pressure position. The non-hatched regionfrom 210° to 266° corresponds to the pressure position of the pressuredevice 198, in which the magnetized characters on the printing mediumcan be read.

The eighth line relates to the position of the pressure device 170 ofthe magnetic strip reading/writing device. In the hatched region from−73° to +262°, the pressure device 170 is in its lifted state andchanges into the lowered state. Only in the narrow region between 262°and 266° of the control shaft 60 does the pressure device 170 rest onthe magnetic head of the reading/writing device 168.

If a printing medium is inserted into the printer, then the receipt stop122 is initially located in its upper position. The printing medium isaligned against the receipt stop 122 with the aid of the alignmentdevice 133. The control shaft 60 is then rotated until the receipt stop122 is lowered, the alignment device 133 is switched off and thepressure rollers 54 can engage with the transport rollers 38.

In order to insert the printing medium between the printing bar 30 andthe pressure film 100, first of all the printing bar 30 has to belowered and the pressure film 100 lifted. This means that the controlshaft 60 has first of all to be rotated onward to 205°. In this positionof the printing bar 30 and of the pressure film 100, the printing mediumcan be moved freely within the printer, so that it can also be broughtinto a position suitable for the reading device 192 or thereading/writing device 168. The pressure devices 198 and 170, whichcorrespond to these reading devices can be operated without the printingbar 30 having to be adjusted first for this purpose, or without thetransport of the printing medium in the printer being hampered.

For the purpose of printing, the printing medium then has to be broughtfirst into a position suitable for printing, between the printing bar 30and the printing head 24. Then, by means of a rotation of the controlshaft 60 into the 90° position, the printing bar 30 is lifted and thepressure film 100 is lowered, whereupon a print can then be made.

List of reference symbols 10 Chassis 78 Helical compression spring 12Base 80 Pin 14 Outer frame 82 Actuating lever 16 Frame wall 84 Pivotaxis 18 Inner frame 86 Lever arm (forked arm) 20 Side wall 88 Lug 22Guide rod 90 Lever arm 24 Dot-matrix printing 92 Free end head 26Carriage 94 Cam discs 28 Toothed belt 96 Pressure device 30 Printing bar98 Film carrier 32 Lower covering 100 Film strip 34 Transport shaft 102Clip 36 Transport shaft 104 Axis 38 Transport rollers 106 Lever 40 Driveroller 108 Helical compression spring 42 Drive roller 110 Extension 44Drive motor 112 First lever arm 46 Shaft 114 Actuating lever 48 Drivepinion 116 Axis 50 Drive belt 118 Second lever arm 52 Tensioning roller120 Cam disc 54 Pressure roller 122 Receipt stop 56 Carrier 124 Carrier58 Transverse strut 126 Stop elements 60 Control shaft 128 Stop elements62 Gear wheel 130 Extension 64 Toothed belt 132 Cam disc 66 Drive pinion133 Alignment device 68 Motor 134 Bearing block 70 Carrier 136 Shaft 72Top rail 138 First coupling sleeve 74 Top side 140 Drive belt 76 Guidenose 142 Second coupling sleeve 144 Coupling claws 212 Lever arm 146Coupling claws 214 Lever arm 148 Alignment roller 216 Hinge 150 Bevelgear wheel 218 Actuating lever 152 Bevel gear wheel 220 Cam disc 154Alignment roller 222 Switching flag 155 Axis 156 Coupling lever 158 Axis160 First lever arm 162 Helical spring 164 Second lever arm 166 Axialcam disc 168 Reading/writing device 170 Pressure device 172 Compressionspring 174 Actuating lever 176 Pin 178 Slot 180 Compression spring 182Top end 184 Pivoting lever 186 Lower end 188 Pin 190 Driver lever 192Reading device 194 Magnetization head 196 Reading head 198 Pressuredevice 200 Swinging arm 202 Shaft 204 Pressure roller 206 Helicalcompression spring 208 Pressure lever 210 Shaft

What is claimed is:
 1. A printer for printing on a printing medium, saidprinter comprising a printer frame, a transport device for moving aprinting medium along a transport path in a transport direction relativeto the printer frame, a printing head, which printing head is adjustablyguided transversely with respect to the transport direction of theprinting medium on a printing head guide, a printing head drive, aprinting bar assigned to the printing head, a printing medium stop whichcan be adjusted between a blocking position, in which it projects intothe transport path of the printing medium, and a release position, meansfor aligning the printing medium relative to the printer frame both insaid transport direction and in a direction transverse to the transportdirection while the printing medium stop is in the blocking position,and a printing control system, wherein a control shaft is rotatablymounted in the printer frame, is driven by a motor controlled by aprinter control system, and bears a plurality of control cams, of whichcams respectively at least one controls the activation of the transportdevice, at least one controls the activation of the alignment means, andat least one controls the adjustment of the printing medium stop,control curves of the control cams being designed such that anactivation zone of the alignment means and an activation zone of theprinting medium stop are located substantially in a deactivation zone ofthe transport device.
 2. The printer as claimed in claim 1, wherein thetransport device comprises at least one driven transport shaft havingtransport rollers, and pressure rollers which are associated with thetransport rollers, the pressure rollers being adjustable between apressure position close to the transport rollers and a rest positionaway from the transport rollers.
 3. The printer as claimed in claim 1,wherein the printing bar can be adjusted in relation to the printinghead, by a control cam on the control shaft, between a printing positionclose to said printing head and a rest position away from the latter,and in that the control curve of the printing bar control cam isdesigned such that the rest position of the printing bar is located inthe activation zone of the transport device.
 4. The printer as claimedin claim 3, wherein an angular range of the control curve of theprinting-bar control cam which corresponds to the printing position ofthe printing bar extends over the deactivation zone and an adjacent partof the activation zone of the transport device.
 5. The printer asclaimed in claim 3, wherein in that parallel to the printing bar thereis arranged a pressure-film strip on a film carrier, which film carrieris adjustable between a position close to the printing bar and aposition away from the printing bar, and in that the adjustment of thefilm carrier is controlled by a film carrier control cam on the controlshaft a control curve of which cam is designed such that when theprinting bar is located in the printing position the film carrier islocated close to the printing bar, and when the film carrier is in therest position the film carrier is located away from the printing bar. 6.The printer as claimed in claim 3, wherein the printer has a readingdevice for reading characters printed with magnetic ink on the printingmedium, and the reading device has at least one magnetic head and aprinting medium pressure device, which printing medium pressure deviceis activated by a control cam on the control shaft, a control curve ofwhich control cam being designed such that the activation zone of theprinting medium pressure device is located in a zone corresponding tothe rest position of the printing bar.
 7. The printer as claimed inclaim 3, wherein the printer has a reading/writing device for readingand writing on a magnetic strip on the printing medium, and in that thereading/writing device has a magnetic head arrangement and a printingmedium pressure device, which can be activated by a control cam on thecontrol shaft, a control curve of this control cam being designed suchthat the activation zone of the printing medium pressure device islocated within the activation zone of the printing medium pressuredevice.
 8. The printer as claimed in claim 1, wherein the control shafthas a switching flag which defines a start position and an end positionand an end position of the control shaft, between which start and endpositions the control shaft can be rotated to and fro.